The present invention relates to photovoltaic arrays and methods of manufacturing photovoltaic arrays. More particularly, the present invention relates to a method and a system for the manufacture of power modules for solar arrays that require less time and labor than required for presently known methods and systems. Various space craft and man-made satellites utilize photovoltaic (“PV”) arrays for recharging of batteries and/or operation of various systems. The PV arrays are a collection of solar cells formed into a unit referred to as a “CIC” (solar cell-interconnect-coverglass). The completed CICs are assembled into strings which are configured into standard power modules (SPMs). The SPMs include interconnected solar cell assemblies, frontside and rearside shielding/coatings, substrate structure, mechanical attachment interfaces, and electrical interconnection interfaces. A number of SPMs are thereafter mechanically and electrically connected to create various blanket architecture aspect ratios, allowing for seamless adaptability to a variety of flexible blanket solar array systems. SPMs manufactured with the disclosed system and according to the disclosed method may be utilized as building blocks to form an Integrated Modular Blanket Assembly (“IMBA”).
U.S. Pat. No. 6,555,739 by Kawam describes a known method of manufacturing a photovoltaic array. According to this method, a CIC is formed by welding or soldering one or more interconnect members (made of a thin ribbon of silver or similar metal) to the solar cell's top surface metal layer. Thereafter, a liquid, translucent silicone adhesive is applied to the solar cell's top surface to bond a layer of doped glass to the cell and interconnect. After all of the solar cells have been formed into CICs, the CICs are assembled into strings. As further described by Kawam, as part of this assembly process, all of the CICs are placed, one at a time, on an alignment tool or jig, with their glass sides down, interleaving the CICs such that the interconnect member from one CIC is resting on the bottom side of an adjacent CIC. The interconnect members are then attached to the bottom side of adjacent CICs by a soldering and/or a welding process. After a desired number of CICs have been so arranged and attached to form a string, the string is transferred to a substrate, which embodies the final solar array configuration. This transfer process is accomplished by first attaching masking tape or similar non-permanent adhesive to the backside of the string, and transporting the taped string, glass side down, onto a transfer device that is fabricated from a sheet of mylar. The transfer device, fabricated from mylar or similar material, allows the array of modules to be handled and lifted into position.
As the next step, the surface of the substrate to be laminated with the string of solar cells is primed by painting a silane material on the substrate surface. As noted by Kawam, the backsides of each of the solar cells are also primed with this material to promote subsequent silicone adhesion. A thin layer of liquid silicone adhesive is then applied to the primed substrate. While the adhesive is still wet and uncured, the string is quickly set into place atop the adhesive applied to the substrate. The string is aligned and individual weights applied to the cells while the adhesive cures, which may take up to a week. After curing, excess adhesive is removed from the PV array.
Kawam notes that the above process was developed in an effort to create a batch process. As noted, first the CICs are assembled, then strings are assembled, and then the strings are transferred to substrates to form the PV arrays. Kawaam notes this manufacturing process involves the handling of the solar cells during at least four separate operations, which results in excessive cost and cycle time. He further notes that the process permits only portions of the assembly to be automated and that this process results in damage to 5% to 8% of the solar cells.
Kawam directs his attention the need to eliminating the need to solder or weld the interconnects to the solar cells, where his solution is to construct strings by bonding the solar cells and interconnect members to the array surface of a substrate with double-sided and pressure sensitive adhesive, and electrically coupling the interconnect members and end members to the solar cells via a dry electrical contact. However, Kawam does not disclose any automated device for the assembly of the strings he discloses. He specifically teaches against a single automated method which produces strings with welded interconnects.
Thus, while there have been some efforts to automate the process, there is not a known system or method which provides for the assembly of an SPM suitable for a space solar array by a single automated device.